Wang Kai-Ge

Third-order ghost interference with thermal light

A scheme for third-order ghost interference with thermal light is proposed. The visibility and resolution of the interference fringe related to the bandwidth of the spatial frequency spectrum of the source are analysed. The results show that the visibility of the third-order ghost interference fringe is much higher than that of the second-order one.

Coalescence and Anti-Coalescence Interference of Two-Photon Wavepacket in a Beam Splitter

We study theoretically the interference of a two-photon wavepacket in a beam splitter. We find that the spectrum symmetry for the two-photon wavepacket dominates the perfect coalescence and anti-coalescence interference. The coalescence interference is unrelated to photon entanglement. Only the anti-coalescence interference has evidence of photon entanglement. We prove that the two-photon wavepacket with an anti-symmetric spectrum is transparent to pass the 50/50 beam splitter, showing perfect anti-coalescence interference.We study a general theory on the interference of two-photon wavepacket in a beam splitter (BS). We find that the perfect coalescence interference requires a symmetric spectrum of two-photon wavepacket which can be entangled or un-entangled. Furthermore, we introduce a two-photon wavepacket with anti-symmetric spectrum, which is related with photon entanglement and shows a perfect anti-coalescence effect. The theory present uniform and complete explanation to two-photon interference.

Improving Visibility of Diffraction Pattern with Pseudo-Thermal Light ⁄

We report an experimental observation of Poissons spot with pseudo-thermal light. The experimental results show that the diffraction pattern disappears in the intensity distribution behind the opaque disc but emerges through both auto-correlation and cross-correlation intensity measurements. The auto-correlation scheme can take care of both better visibility and higher resolution of the diffraction pattern under the condition that the thermal light source has a larger spectral bandwidth.

Novel Ghost Imaging Method for a Pure Phase Object

We propose a novel ghost imaging scheme which is especially served to a pure phase object A spatially incoherent beam is mixed with a coherent beam of the same frequency field by a beamsplitter. Then we perform the ghost imaging scheme using the mixed beam. Our theoretical result shows that this approach is capable of reconstructing a pure phase object in joint-intensity measurement. The visibility of the images is also analysed for two pure phase objects, an optical wedge and a phase grating.

Hanbury-Brown and Twiss type double-slit interference with photorefractive fanning light

This paper reports that when an intense extraordinary-polarized laser beam illuminates a photorefractive BaTiO3 crystal, the dynamic beam fanning light is formed to be a thermal-like light source with a long correlation time and wide spectral bandwidth. The experimental results of the first- and second-order double-slit interference with such photorefractive fanning light source, can be understood with the theoretical simulation in terms of Hanbury-Brown and Twiss effect.

From Hanbury–Brown and Twiss Experiment to the Second-Order Double-Slit Interference for Incoherent Light

In this review article, we discuss both experimentally and theoretically the second-order double-slit interference for a thermal light source which is random in transverse propagating direction. We show that when the bandwidth of the noise spectrum is increased, the first-order interference pattern disappears while the sub-wavelength pattern fringe emerges in the intensity correlation measurement. Our theoretical description, which is carried out in contrast with coherent light and two-photon state sources, demonstrates that this effect can be explained in accordance with the Hanbury–Brown and Twiss experiment.

Super-Resolution of Interference Pattern with Independent Laser Beams

We propose a new scheme to achieve sub-Rayleigh resolution of interference pattern with independent laser beams. We perform an experimental observation of a double-slit interference with two orthogonally polarized laser beams. The resolution of the interference pattern measured by a two-photon detection is doubled provided the two beams illuminate the double-slit with certain incident angles. The scheme is simple and can be in favor of both high intensity and perfect visibility.We propose a scheme to achieve super-resolution of interference pattern with independent laser beams. We perform an experimental observation of a double-slit interference with two orthogonally polarized laser beams. The resolution of the interference pattern measured by a two-photon detection is doubled provided the two beams illuminate the double-slit with certain incident angles. The scheme is simple and can favour both high intensity and perfect visibility.

Transparency induced by two-photon interference in a beam splitter

We propose a special two-photon state which is completely transparent in a 50/50 beam splitter. This effect is caused by the destructive two-photon interference and shows the signature of photon entanglement. We find that the symmetry of the two-photon spectrum plays the key role for the properties of two-photon interference.

Generation of Pair Coherent States in Two-dimensional Trapped Ion

We consider a two-dimensional (2D) trapped ion model in which two laser beams drive the corresponding vibrational motions and are carrier resonant with the two-level of the ion. Due to the coherent superposition of two sub-Rabi oscillations involved in the bimodal vibrations, the Rabi frequency degeneration and offset may occur in this model. This provides the possibility of generating the pair coherent state in the 2D trapped ion.

Color Ghost Imaging with Pseudo-White-Thermal Light

A pseudo-white-thermal light source is prepared by projecting three (red, green, and blue) laser beams onto a rotating ground glass disk. Based on the RGB color model, we investigate the color Hanbury-Brown-Twiss (HBT) effect and color ghost imaging with thermal light. The color HBT effect indicates that photons of the same color will bunch. This fact ensures the chromatic discrimination power of ghost imaging with thermal light. We retrieve the RGB ingredients of the object through intensity correlation measurements. A method of white balance to properly form the ghost images is proposed.